Abstract: The existence ofβ-carotene in the fermentation broth of Rhodotorula was identified by HPLC, and its in vitro cleavage into retinol also known as vitamin A byβ-carotene 15,15＇-monooxygenase from chicken intestinal mucosa was studied. The optimum reaction conditions for converting 123 mg/Lβ-carotene concentrate were determined to be: pH 8.0, 3.5 mmol/L deoxycholate, 0.5 mmol/L d-α-tocopherol and 0.25 g/100 mL Tween-40. Under the optimum conditions, 7 h incubation of 2.58 nmol/(mg·h )β-carotene 15,15＇-monooxygenase in 37 ℃ water bath with shaking produced 40.1 mg/L retinol, with a conversion yield of 32.6%.

Key words: Rhodotorula, β-carotene, β-carotene-15,15′-monooxygenase, retinol, reaction conditions optimization